int countStudents(int* students, int studentsSize, int* sandwiches, int sandwichesSize){
      int cnt=studentsSize;
      int front=0;
      int index=0;
      while(index<cnt){
      if(students[front]==sandwiches[front]){
        cnt--;
        front++;
        index=0;
      }else{
        int t=students[front];
        for(int i=front;i<studentsSize-1;i++){
          students[i]=students[i+1];
        }
        students[studentsSize-1]=t;
        index++;
     }
    }
    return cnt;
}
